Highly oxidized organic aerosols in Beijing: Possible contribution of aqueous-phase chemistry

Feng, Zemin; Zheng, Feixue; Yan, Chao; Fu, Peng; Zhang, Yusheng; Lian, Chaofan; Wang, Weigang; Cai, Jing; Du, Wei; Chu, Biwu; Wang, Yonghong; Kangasluoma, Juha; Bianchi, Federico; Petäj̈ä, Tuukka; Kulmala, Markku

doi:10.1016/j.atmosenv.2022.118971

Cited by 7 publications

(8 citation statements)

References 114 publications

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“…Even though other photochemical processes could affect the formation of oxygenated OA, the higher presence of cloud events in the last part of the campaign suggests that cloud processing at Réunion has a potential role in forming highly oxidized organic aerosols. These observations, although low, are in line with increases reported in previous studies, where an increase (15% to 25%) of MOOA aerosol was observed as a function of relative humidity and aerosol liquid water content. ,,, …”

Section: Resultssupporting

confidence: 92%

“…These observations, although low, are in line with increases reported in previous studies, where an increase (15% to 25% 27 ) of MOOA aerosol was observed as a function of relative humidity and aerosol liquid water content. 20,25,26,119 Similar changes were observed from the offline PM 10 filter measurements with a 48% increase in sulfate and a 70% increase in ammonium concentrations, indicating that aqueous processing potentially influences all the aerosol size fractions. As previously described, oxalic acid concentrations measured in PM 10 show a 2-fold increase during Period 2 compared to Period 1 and the concentrations of malonic and succinic acids (Figure S8).…”

Section: Aerosol Processing Under Cloud Conditionssupporting

confidence: 67%

“…Moreover, recent studies have shown that the aqueous-phase processing of aerosols has a dominant impact on the formation of more oxidized SOA (more oxidized organic aerosol, MOOA). The contribution of MOOA to total organic aerosols increases as a function of relative humidity or liquid water content. ,,− …”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Sources, Precursors, and Processing of Aerosols at a High-Altitude Tropical Site

Dominutti

Chevassus

Baray

et al. 2022

ACS Earth Space Chem.

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This work presents the results from a set of aerosol-and gas-phase measurements collected during the BIO-MAI ̈DO field campaign in Reúnion between March 8 and April 5, 2019. Several offline and online sampling devices were installed at the Mai ̈do Observatory (MO), a remote high-altitude site in the Southern Hemisphere, allowing the physical and chemical characterization of atmospheric aerosols and gases. The evaluation of short-lived gas-phase measurements allows us to conclude that air masses sampled during this period contained little or no anthropogenic influence. The dominance of sulfate and organic species in the submicron fraction of the aerosol is similar to that measured at other coastal sites. Carboxylic acids on PM 10 showed a significant contribution of oxalic acid, a typical tracer of aqueous processed air masses, increasing at the end of the campaign. This result agrees with the positive matrix factorization analysis of the submicron organic aerosol, where more oxidized organic aerosols (MOOAs) dominated the organic aerosol with an increasing contribution toward the end of the campaign. Using a combination of air mass trajectories (model predictions), it was possible to assess the impact of aqueous phase processing on the formation of secondary organic aerosols (SOAs). Our results show how specific chemical signatures and physical properties of air masses, possibly affected by cloud processing, can be identified at Reúnion. These changes in properties are represented by a shift in aerosol size distribution to large diameters and an increased contribution of secondary sulfate and organic aerosols after cloud processing.

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Section: Resultssupporting

confidence: 92%

Section: Aerosol Processing Under Cloud Conditionssupporting

confidence: 67%

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Evaluation of the Sources, Precursors, and Processing of Aerosols at a High-Altitude Tropical Site

Dominutti

Chevassus

Baray

et al. 2022

ACS Earth Space Chem.

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“…Due to their high values of Henry’s law constants (10 7 –10 13 M × atm –1 ), TAs and acidic dimers reside almost entirely in cloud and fog water. − Therefore, such molecules are likely to undergo aqueous chemical aging, which can contribute to the formation of low-volatility organics in the atmosphere. ,− Aqueous photochemical processing alters the molecular composition and physicochemical as well as optical properties of SOAs. − Consequently, the formation and processing of SOAs in the aqueous phase have a direct impact on their cloud condensation nuclei and ice-nuclei activity, particle mass and number concentrations as well as the health effects of atmospheric PM. − Because liquid water is a major tropospheric constituent, , formations of aqueous SOAs ( aq SOAs) are expected to significantly contribute to the global budget of organic aerosols . At the same time, the formation and processing of aq SOAs , are still not well characterized, ,, which limits our understating of the climate forcing of organic aerosols.…”

Section: Introductionmentioning

confidence: 99%

Aging of α-Pinene Secondary Organic Aerosol by Hydroxyl Radicals in the Aqueous Phase: Kinetics and Products

Witkowski

Alsharafi

Błaziak

et al. 2023

Environ. Sci. Technol.

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The reaction of hydroxyl radicals (OH) with a water-soluble fraction of the α-pinene secondary organic aerosol (SOA) was investigated using liquid chromatography coupled with negative electrospray ionization mass spectrometry. The SOA was generated by the dark ozonolysis of α-pinene, extracted into the water, and subjected to chemical aging by the OH. Bimolecular reaction rate coefficients (k OH) for the oxidation of terpenoic acids by the OH were measured using the relative rate method. The unaged SOA was dominated by the cyclobutyl-ring-retaining compounds, primarily cis-pinonic, cis-pinic, and hydroxy-pinonic acids. Aqueous oxidation by the OH resulted in the removal of early-stage products and dimers, including well-known oligomers with MW = 358 and 368 Da. Furthermore, a 2- to 5-fold increase in the concentration of cyclobutyl-ring-opening products was observed, including terpenylic and diaterpenylic acids and diaterpenylic acid acetate as well as some of the newly identified OH aging markers. At the same time, results obtained from the kinetic box model showed a high degree of SOA fragmentation following the reaction with the OH, which indicates that non-radical reactions occurring during the evaporation of water likely contribute to the high yields of terpenoic aqSOAs reported previously. The estimated atmospheric lifetimes showed that in clouds, terpenoic acids react with the OH exclusively in the aqueous phase. Aqueous OH aging of the α-pinene SOA results in a 10% increase of the average O/C ratio and a 3-fold decrease in the average k OH value, which is likely to affect the cloud condensation nuclei activity of the aqSOA formed after the evaporation of water.

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“…annual average concentration of PM 2.5 reached the Chinese National Ambient Air Quality Standard for the first time in 2021 (33 μg m -3 ). However, polluted events still occurred occasionally, particularly during wintertime with stagnant meteorological conditions and high anthropogenic emissions (Lei et al, 2021b;Xu et al, 2022;Feng et al, 2022;Zhou et al, 2023). Shortterm emission controls can improve air quality by reducing anthropogenic emissions temporarily, for example, the Beijing 2008 Summer Olympics (Wang et al, 2010;Okuda et al, 2011;Zhou et al, 2010), the 2014 Asia-Pacific Economic Cooperation (APEC) summit (Han et al, 2015;Gao et al, 2017;Ren et al, 2018), and the 2020 lockdown due to the corona virus disease (COVID-19) (Sun et al, 2020;Chang et al, 2022;Rajesh and Ramachandran, 2022;Zhang et al, 2022a).…”

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confidence: 99%

Mixing state and effective density of aerosol particles during the Beijing 2022 Olympic Winter Games

Sun

Liu

et al. 2023

Preprint

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Abstract. Mixing state and density are two key parameters of aerosol particles affecting their impacts on radiative forcing and human health. Here a single particle aerosol mass spectrometer in tandem with a differential mobility analyzer and an aerodynamic aerosol classifier was deployed during the Beijing 2022 Olympic Winter Games (OWG) to investigate the impacts of emission controls on particle mixing state and density. Nearly 760,000 particles were detected, which were classified into seven major classes. Our results showed the dominance of carbonaceous particles comprising mainly Total-EC (13.4 %), Total-OC (10.5 %) and Total-ECOC (47.1 %). Particularly, the particles containing organic carbon and sulfate were enhanced significantly during OWG although those from primary emissions decreased. The composition of carbonaceous particles also changed significantly which was characterized by the decreases in EC-NS, KEC-N, and amine-containing particles, and increase in ECOC-NS. This result indicates that emission controls during OWG reduced the mixing of elemental carbon (EC) with inorganic aerosol species and amines, yet increased the mixing of EC with organic aerosol. The average effective density (ρeff) of aerosol particles (150–300 nm) was 1.20 g cm−3 with higher values during OWG (1.26 g cm−3) due to the increase in secondary particle contribution. The two types of fresh particles, i.e., Total-EC and high molecular weight organic matter presented the lowest ρeff (0.97 g cm−3 and 0.87 g cm−3, respectively). In addition, the ρeff of most particles increased as the increases in pollution levels and relative humidity, yet varied differently for different types of particles, highlighting the impacts of aging and formation processes on the changes of particle density and mixing state.

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Highly oxidized organic aerosols in Beijing: Possible contribution of aqueous-phase chemistry

Cited by 7 publications

References 114 publications

Evaluation of the Sources, Precursors, and Processing of Aerosols at a High-Altitude Tropical Site

Evaluation of the Sources, Precursors, and Processing of Aerosols at a High-Altitude Tropical Site

Aging of α-Pinene Secondary Organic Aerosol by Hydroxyl Radicals in the Aqueous Phase: Kinetics and Products

Mixing state and effective density of aerosol particles during the Beijing 2022 Olympic Winter Games

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